Magnetic switch mounting means for a fluid motor unit

ABSTRACT

An adjustable form of magnetic reed switch mounting means which utilizes a movable arm member in a slotted track member adapted to be mounted along the exterior cylinder wall of the air cylinder or other fluid motor unit. A preferred form of the track has a cross section curved interior surface while the base portion of the arm member that moves in the track has corresponding curvature and is capable of having transverse angular rotation with respect to the track and to the air cylinder so as to be able to fit against different sized housings.

United States Patent Gasper et al.

[ Feb. 1, 1972 1541 MAGNETIC SWITCH MOUNTING MEANS FOR A FLUID MOTOR UNIT [72] Inventors: Ralph L. Gasper, Lansing; Donald E. Riorden, Tinley Park, both of 111.

[73] Assignee: Bimba Manufacturing Company, Monee,

[22] Filed: Mar. 17, 1971 [211 App1.No.: 125,282

[52} 11.8. CI ..335/205, ZOO/81.9 M [51] Int. Cl. ..H0lh 9/00 5s FieldofSearch ..3 3s/20s,151;20o/s1.9M r

[56] References Cited UNITED STATES PATENTS 2,600,011 6/1952 MacDonald et a1. .335/205 mgs.

3,507,359 4/1970 Warnock ZOO/819M 3,555,221 1/1971 Booth ..335/205 3,562,455 2/1971 McQueen...L.... ..200/8l.9M

Primary Examiner-Harold Broorne Attorney-Philip T. Liggett I An adjustable'formof magnetic reed sxvitch mounting means which utilizes agmmable arm member in a slotted track member adapted tobe mounted along the exterior cylinder wall of the air cylinder or other'fluid motor unit. A preferred form of the track has a cross section curved interior surface while'the' base portionof the arm memberthat moves in the track has corresponding curvature and is capable of having transverse angular rotation with respect to the track and to the air cylinder so as to be able to fit against different sized hous- 6 Claims, 5 Drawing Figures PATENIEDFEB um 316391868 nvvnvrores:

70 "I Ralph L. Gaspar Donald E. Riordan E-- A TTO'fi/VEY v MAGNETIC SWITCH MOUNTING MEANS FOR A FLUID MOTOR UNIT The present invention is directed to an adjustable type of mounting means for holding a magnetic reed switch along side of a cylindrical form of housing. More particularly, the present mounting arrangement incorporates a switch holding arm member that can move longitudinally in a track section and, additionally, have transverse rotation with respect thereto such that a magnetic switch can be suitably held adjacent various diameter cylinders or piston housings in turn having a magnet holding reciprocating piston.

In connection with the commercial operation of fluid motors, such as with air cylinders, or with other piston-type units, there is the frequent desire, or need, to have switch means to note the position of the piston, count piston strokes, or whatever. In earlier systems, there were limit switches which were mounted adjacent the power cylinder and such switch means were actuated by strike plates, or arm means mounted on to the moving piston rods of the units. At the present time, a magnet, or magnetic compound, can be mounted internally onto the reciprocating piston member and inside the motor housing and an externally mounted magnetic reed switch can be utilized to note the piston positioning. For example, the reed switch can be connected into an electrical circuit so as to count strokes, operate another unit, or do any other desired function. Various types of reed switch mounting means have been tried and used with air cylinders; however, most forms have not been fully adjustable to accommodate different sized units, while others have not been adapted to withstand the high number of jarring movements encountered with piston type motors, pumps, and the like.

It is thus a principal object of the present invention to provide a switch mounting arrangement which permits full longitudinal adjustment as well as transverse rotational adjustment so as to permit a proper fit of the magnetic switch to varying sized cylindrical units.

It is a further object of the invention to provide an elongated track section with an internal slot which is at least partially curved to accommodate a movable arrn member that also has partially curved base section to fit into the slot and be capable of rotating transversely through an arc whereby there is adjustability at the other end of the arm with respect to the cylinder housing.

In a broad aspect, the invention provides in combination with piston housing means the improved arrangement of a magnetic switch system and mounting means therefore, which comprises in combination, a magnet mounted on at least a portion of a nonmagnetic piston in the housing, a magnetic reed switch in adjustable support means along the exterior of the housing wall to be activated by the magnet on said piston, and said switch support means including a longitudinal slotted track member and an arm member, with the latter having a switch holding means at an outer extremity and a base section sized to engage and slidably fit within said slotted track member, said base section additionally providing at least some degree of transverse angular rotation with the track member, whereby said arm member can fit against exterior wall of varying diameter housings.

In a simplified and preferred reed switch mounting arrangement, the elongated track member which is attached to the exterior cylinder housing will have an internal slot that is at least partially curved in its cross-sectional aspect whereby a matching base section of a movable arm member can be capable of rotating to some degree transversely with respect to he track member. This partial rotation will permit adjustment of the outer end of the arm member to in turn permit a magnetic switch to lay adjacent to exterior wall of the housing for different sizes and types of piston housings. In other words, the same mounting system is readily adaptable for use on the varying diameters of air cylinders, or other fluid motor means.

Various types of holding means can be used to fix the positioning of the arm member within the slotted track section; however, setscrew means through the base of the arm member will provide a simplified and easily operated type of locking means to fix the positioning of the arm member at a desired location, The longitudinal adjustment afforded by the slidable arm member within the slot of the track permits full adjustment for the positioning of the switch means on the piston housing and thus the adaptability to operate for any length of stroke of the piston within the housing.

Various types of magnetic means may be used on the movable piston within the fluid motor means, or other pistonoperated unit. In those instances where the piston will not rotate with respect to the housing, a magnet can be inserted into alportion of the piston member at a given location which will be in alignment with the exterior positioning of the reed switch member; however, in many types of fluid motor operations, there can be rotation of the piston and piston rod with respect to the exterior cylinder wall and housing, and it is thus necessary to have a series of magnets mounted around the piston'member or, alternatively, a use continuous magnet that is fully circumferential around the piston member. It is not intended to limit the present invention to any one type of magnet nor to any one system of mounting the magnet to the piston member. It is, however, advisable to have a wearing surface or wear strip mounted over themagnet so that there is no danger of the magnet actually coming in contact with the interior;wa.ll of the cylinder and causing wall damage. In one type of installation, there may be the. use of magnetizable particles compounded into a plastic material which, in turn, will permit the placement of the particles within a circumferential groove of the piston member. Specifically, there are magnetizable materials now commercially available, such as barium ferrite particles within a nitrile base rubber material, such that the particles can be maintained stable within the presence of lubricating oils that may be present within an air cylinder or other fluid power unit. The ferrite material can be permanently magnetized and the magnetization accomplished before an assembly of the piston into the cylinder or housing. In addition, there may be a steel band circumferentially positioned around the piston member within the bottom of the groove section for the magnetic material and such band serving to concentrate the flux lines away from the central portion of the piston and toward the switch side of the assembly. Still further, it may be of particular advantage to provide a Teflon layer or other equivalent type wear strip around the barium ferrite-material such that the latter will not come into contact with the inside of the cylinder wall of the unit.

It may also be noted that the present switch mounting arrangement can be used to advantage in holding more than one switcharm member so that a plurality of reed switch means may be mounted along the piston housing within the same elongated track section. Alternatively, a plurality of mounting track members can be spaced at different locations on the housing wall and each track member, in turn, may hold one or more magnetic switch arm members and switch means. Thus, a plurality of switching operations may be effected by each strokeof the piston within the motor unit.

Referenceto the accompanying drawing and the following description thereof will serve to better describe the present improved switch mounting assembly for use with a piston containing unit, such as an aircylinder or other fluid motor unit.

FIG. 1 of the drawing is a diagrammatic elevational view, partially in section, indicating magnet means on the internal piston and a switch holding track and arm means on the exterior of the housing;

FIG. 2 of the drawing is a cross-sectional view through the longitudinal track and cylindrical form housing to better indicate the positioning of the switch holding arm against the exterior wall of the housing, as indicated by line 2-2 in FIG. 1.

FIGS. 3 and 30 indicate, in slightly enlarged cross-sectional views, the rotational movement that the switch holding arm member can take with respect to the longitudinal track member to thus permit adjustability of the arm member to different sized housing. 7

FIG. 4 of the drawing shows, also in an enlarged cross-sec tional view, the angular placement of setscrew means to increase the effective locking of the switch mounting arm against the body of the cylinder.

Referring now particularly to FIGS. 1 and 2 of the drawing, there is shown a fluid motor unit having a cylindrical body section or housing 1, end members 2 and 3 and an internal piston member 4 with its accompanying piston rod means 5. Attached to the exterior of the motor unit and along side cylindrical wall 1 is a track member 6 which, in turn, holds a slidable switch holding arm member 7. The track member 6 is indicated as being removably attached to the housing by threaded cap screw members 8 and 9 which, in turn, engage the respective end members 2 and 3. There is also indicated in the present embodiment of FIG. 1 a pair of fluid ports or openings 10 and 11 within the respective end members 2 and 3 such that piston member 4 can be caused to have the desired reciprocating operation in housing 1.

Although various types of magnet means may be mounted within or around piston member 4, a preferred arrangement permits rotational movement of the piston 4 to take place and will have a fully circumferential magnet means within a grooved portion of the piston. In FIG. 1, there is indicated a third groove, between those for O-rings or other type seal members 12 and 13, and this middle groove accommodates a circular magnet. Specifically, in the present embodiment, there is shown an inner steel band 14, which will serve to concentrate flux lines away from the central portion of the piston, and a layer of barium ferrite particles 15 within a suitable carrying material such as nitrile base rubber. In addition, over the barium ferrite particles, there is a layer or wear strip section of Teflon 16 which will be in contact with the inside wall of .the cylindrical housing 1. The Teflon wear strip will, of course, preclude damage by the abrasive magnetic material in the layer 15.

As best shown by FIG. 2, a magnetic reed switch 17 will be held in the end of arm member 7 such that it is relatively close to the exterior sidewall of housing 1. The reed switch may be inserted into an opening and held therein by suitable high strength adhesive means or, optionally, by a suitable halfround clamp arrangement that may be provided to hold the switch 17 at the end of the arm member 7. As hereinbefore noted, arm member 7 will be longitudinally positionable with respect to the length of the motor unit by being slidable within track section 6. In other words, an inverted T-shaped base ember 7a is adapted to conform with the shape of the interior slot portion of track 6 and longitudinally slidable therein. A setscrew means 18 is shown for locking arm member 7 at a desired position within track 6; however, there may be setscrews through the side of track 6 to engage andlock the arm member. The longitudinal adjustability, of course, provides any desired longitudinal location of switch means 17 withv respect to the longitudinal movement of piston member 4, as determined by its stroke, whereby the switch openings and closings of 17 can be caused to function for any desired movements or positions.

In the enlarged cross-sectional view of FIG. 3, there is more clearly shown a semicylindrical inner surface 6 along the inner slot portion of track 6 and a matching semicylindrical surface 7 on the exterior of the base portion 7a of arm member 7. Thus, with some space provided below base portion 7a and the bottom portion of track section 6, there is room for angular rotation between arm member 7 and track member 6. For example, angular rotation 0 is shown between base portion 7a of arm member 7 and the normal or vertical axis throughout the central portion of track member 6. Typically, after arm member 7, with reed switch means 17, has been positioned to contact the outer cylindrical surface of housing 1, there is the tightening of setscrew member 18 to lock the arm member 7 in the desired angular position, as well as in a desired longitudinal position.

In FIG. 3a of the drawing, there is shown a reverse or opposite angular positioning 0 between base section 7a and track member 6 such that the other cantilevering arm portion of arm member 7 can accommodate a larger diameter housing 1'. Generally, a relatively small amount of angular rotation will permit the switch holding arm 7 to accommodate itself to different diameter cylinders or housings; however, it will be seen that by providing ample spacing for rotation of base portion 7a in the bottom portion of the slot track member 6 and sufficient lateral room in the top or neck portion of the slot there can be a relativelylarge amount of rotational movement between arm member 7 and track 6.

Referring now to FIG. 4 of the drawing, there is shown the special placement of the setscrew member 18 at an angle a with respect to the normal axis of the base portion 7a whereby any lifting of the arm member 7, which holds the magnetic switch, will make the inner point or edge of the setscrew tend to dig into the base of the track 6. In other words, by having the angular placement of the top of the setscrew l8 sloping toward the cantilevering arm portion 7, as shown by the angle a in FIG. 4, there is an increase in the bite effect of the lower end of set screw 18 into track 6 upon any attempt to lift up arm portion 7. The result is an increase in effective locking force of the screw as compared to a situation such as shown in FIG. 30.

It will be obvious to those skilled in the art that minor variations in design and configuration may well be made with respect to the slot in the track member 6 as well as with respect to the arm member and T-portion thereon which will accommodate itself to the slot means. However, in all cases and in accordance with the present invention, it is required that there be a curved exterior surface on a base portion 7a and a curved wall portion to the slot 6 in track member 6 such that the transverse angular rotation between the two members is obtainable to in turn permit the switch holding end of arm member 7 to accommodate itself to various diameters of fluid power units. The indication of a screw 18 is also merely diagrammatic and other types of setscrews or clamping means, may well be used to provide the fixed positioning of arm member 7 in track member 6. Still further, various types of clamps or holding means may well be used at the end of arm member 7 to engage the reed switch means 17 and it is not intended to limit the holding of the latter onto the arm member by adhesives, although epoxy cements and other high strength adhesive materials may well be used to advantage for the tight mounting of a magnetic reed switch to an arm means. As hereinbefore indicated, it is not intended to limit the present switch mounting means with its adjustability features to merely an air cylinder, inasmuch as the same type of magnet arrangement and mounting system may well be used in connection with other type pistons and housings for various types of fluid motors or piston containing power units, such as pumps, compressors, and the like.

We claim as our invention:

1. In combination with piston housing means, the improved arrangement of a magnetic switch and mounting means therefore, which comprises in combination, a magnet mounted on at least a portion of a nonmagnetic piston in the housing, a magnetic reed switch in adjustable support means along the exterior of the housing wall to be activated by the magnet on said piston, and said switch support means including a longitudinal slotted track member and an arm member, with the latter having a switch holding means at an outer extremity and a base section sized to engage and slidably fit within said slotted track member, said base section additionally providing at least some degree of transverse angular rotation with the slotted track member, whereby said arm member can fit against the exterior wall of varying diameter housings.

2. The magnetic switch mounting means of claim 1 further characterized in that said track member has a longitudinal slot with at least a portion of its transverse cross section being curved and the base section of the arm member slidable therein is similarly curved to be transversely rotatable within said slot as well as longitudinally movable therein.

3. The magnetic switch mounting means of claim 1 further characterized in that setscrew means is utilized between said base section of the arm member and said track member whereby the arm member may be fixably held in the track member.

4. The magnetic switch system of claim 1 further characterized in that the magnet on the piston within the piston housing will be fully circumferential around the piston, whereby the track can be along any portion of the housing and the magnetic switch in said arm member can extend from either side of said track member and be operable with respect to longitudinal movement of the piston in said housing.

5. The magnetic switch system of claim 4 still further characterized in that the circumferential magnet mounted on said piston is encompassed by a Teflon wear strip to preclude abrasive contact of any magnet material against the interior wall of the housing.

6. The magnetic switch system of claim 1 further characterized in that an angularly positioned setscrew means is provided through said base section to engage the interior of said track member, with said setscrew means being positioned angularly with respect to the normal axis of said base section such that the upper end of the setscrew slopes toward the side of the arm member having the switch holding means whereby there is an increase in the locking effectiveness of said setscrew means for holding the arm member in a nonliftable position. 

1. In combination with piston housing means, the improved arrangement of a magnetic switch and mounting means therefore, which comprises in combination, a magnet mounted on at least a portion of a nonmagnetic piston in the housing, a magnetic reed switch in adjustable support means along the exterior of the housing wall to be activated by the magnet on said piston, and said switch support means including a longitudinal slotted track member and an arm member, with the latter having a switch holding means at an outer extremity and a base section sized to engage and slidably fit within said slotted track member, said base section additionally providing at least some degree of transverse angular rotation with the slotted track member, whereby said arm member can fit against the exterior wall of varying diameter housings.
 2. The magnetic switch mounting means of claim 1 further characterized in that said track member has a longitudinal slot with at least a portion of its transverse cross section being curved and the base section of the arm member slidable therein is similarly curved to be transversely rotatable within said slot as well as longitudinally movable therein.
 3. The magnetic switch mounting means of claim 1 further characterized in that setscrew means is utilized between said base section of the arm member and said track member whereby the arm member may be fixably held in the track member.
 4. The magnetic switch system of claim 1 further characterized in that the magnet on the piston within the piston housing will be fully circumferential around the piston, whereby the track can be along any portion of the housing and the magnetic switch in said arm member can extend from either side of said track member and be operable with respect to longitudinal movement of the piston in said housing.
 5. The magnetic switch system of claim 4 still further characterized in that the circumferential magnet mounted on said piston is encompassed by a Teflon wear strip to preclude abrasive contact of any magnet material against the interior wall of the housing.
 6. The magnetic switch system of claim 1 further characterized in that an angularly positioned setscrew means is provided through said base section to engage the interior of said track member, with said setscrew means being positioned angularly with respect to the normal axis of said base section such that the upper end of the setscrew slopes toward the side of the arm member having the switch holding means whereby there is an increase in the locking effectiveness of said setscrew means for holding the arm member in a nonliftable position. 